Automatic stop mechanism for record changers



Dec. 11, 1951 s. A. STOLBERG AUTOMATIC STOP MECHANISM FOR RECORD CHANGERS Filed Aug. 30, 1945 4 Sheets-Sheet 1 INVENTOR. SVenAfflvlbe Dec. 11, 1951 s. A. STOLBERG AUTOMATIC STOP MECHANISM FOR RECORD CHANGERS 4 Sheefs-Sheec 2 Filed Aug. 30, 1945 Mal/Q I INVENTOR. Sven A. Sfolberg,

Dec. 11, 1951 s. A. STOLBERG AUTOMATIC STOP MECHANISM FOR RECORD CHANGEIRS 4 Sheet-s-Sheei 3 Filed Aug. 30, 1945 INVENTOR. SvenA.ST |ber' D 1951 s. A. STOLBERG 2,578,378

AUTOMATIC STOP MECHANISM FOR RECORD CHANGERS Filed Aug. 30, 1945 1 4 Sheets-Sheet '4 .(N VEN TOR.

Patented Dec. 11, 1951 AUTOMATIC STOP MECHANISM FOR RECORD OHANGERS Sven A. Stolberg, Chicago, Ill., assignor, by mesne assignments, to Raytheon Manufacturing Company, Newton, Mass, a corporation of Delaware Application August 30, 1945, Serial No. 613,470

4 Claims.

This invention relates to improvements in record-changing phonographs, and the like. Generally speaking, the present invention concerns itself with improvements in a stop mechanism whereby specified stopping operations will be instituted when the final record of a series has been moved or released to playing position.

Many record-changing phonographs are provided with electrically driven motor drives, including motors which run continuously, together with means to discontinue drive from such motors to the other mechanisms under specified conditions. When such arrangements are used it is evident that the motor will continue to operate until current supply thereto is discontinued by a suitable switch mechanism. Heretofore such switch mechanism has been manually operated, so that shutting oif of the motor has involved an intentional switch opening manual operation. Means have heretofore been provided whereby the drive from such running motor to the one-cycle cam will be discontinued or made discontinuable when the final record has been released to playing position, but leaving the motor itself still running. Such a scheme is disclosed, for example, in my co-pending application for Letters Patent of the United States, Serial No. 607,878, filed July 30, 1945, for Record-Changers (now U. S. Patent 2,564,455). In the disclosure of that application the release of the final record to playing position serves to set the position of stop devices so that when the one-cycle cam is brought into cyclic operation at the completion of playing of such final record, said one-cycle cams drive will be discontinued prior to completion of the cycle, and preferably with the tone-arm shifted to its outermost position. In that disclosure, however, the driving motor is left in running condition, since the stoppage of the one-cycle cam does not of itself discontinue supply of current to the motor. In the scheme of that application, also, the subsequent movement of certain parts, incident to preparation for insertion of additional records into record feeding position, serves to release such stop mechanism so that, the motor being still in operation, the one-cycle cam will continue and complete its cyclic movement. Such completing movement of the one-cycle cam serves to release one of the newly supplied records into playing position, and to place the tonearm at the correct position for commencement of playing of such newly supplied record. However, it is still noted that the motor operation in that disclosure is not discontinued merely by the releasing of the final record to playing position.

It is a principal object of the present invention to make provision of means to interrupt supply of current to the driving motor upon release of the final record to playing position, and only when the playing of that finally released record has been completed. ,In other words, the present application makes provision for discontinuing current supply to the driving motor when such finally released record has been fully played, and when the tone-arm has been lifted away from such record and has been swung outwardly to its extreme position, free of the records on the turntable. Specifically, the means disclosed herein is such that when the final record has been released to playing position, suitable devices are moved to tripping position, but are not then tripped, so that the supply of current to the driving motor still continues; and the means herein disclosed is further such that thereafter, and as the one-cycle cam continues its cyclic movement, a trigger device is released, thereby permitting the switch device to move to open position, and discontinue current supply to the motor. In other Words, the disclosures herein are such that interruption of current supply occurs when playing of the finally released record has been completed, and when the onecycle cam has completed its cyclic operation to the point of raising the tone-arm and swinging it to its outermost position free of the record on the turntable.

Specifically, I have provided means such as just above stated, in combination with means to also interrupt the operation of the one-cycle cam prior to its movement to a position where the record releasing means is functioned. In this connection, I have combined the features of the present invention with the disclosures of such a stop mechanism as that disclosed in my aforesaid application, Serial No. 607,878; but I wish it distinctly understood that I do not intend to limit the features of the present invention with the one-cycle cam stopping device of said earlier application, nor to any one-cycle cam stopping device, except as I may do so in the claims to follow.

A further feature of the present invention relates to the provision of means to re-set the motor switch into current supplying position when the motor operation is to be again resumed. In this connection I may mention that in the said earlier application, Serial No. 607,878, I have disclosed a manually operable button or other suitable device, the position of which may be set to any one of several selected positions. Such positions may include, for example, Stop, Manual, Automatic and Reject. Such a manually settable device is also disclosed in vari ous other co-pending applications filed by me or by others, and I mention said application, Serial No. 607,878, merely by way of illustration. It is a further feature of the present application that i have herein disclosed means whereby the movement or such manually controlled button or other device may also serve to re-set or pro-set such switch to its closed position, thus making it possible to again bring the motor into opera tion by current supply thereto.

It is here noted that it is sometimes desirable to shut on current supply to the motor irrespective of any functioning of the automatic current discontinuing operation herein mentioned, so that current supply may be completely stopped manually and irrespective of any automatic function. In this connection, it is here noted that the specific means herein disclosed for effecting this specific operation is placed in series with the automatic switch means, so that both must be closed in order to bring and retain the motor in operation.

It is a further object of the invention to provide a stop means which may be readily cornbined with the stop device for the one-cycle cam, or with the means disclosed in said earlier application, so that the means of the present application may, on occasion, be readily used with such earlier features.

Other objects and uses of the present invention will appear from a detailed description of the same, which consists in the features of construction and combinations of parts hereinafter described and claimed.

In the drawings:

Figure 1 shows a plan view of a typical recordchanger embodying the features of the present invention;

Figure 2 shows a side elevation of the record supporting stand for the edge portions of the records, the head of said stand being shown in its fully lowered position, such as it assumes when the final record has been released to playing position;

Figure 3 shows a vertical section through the stand of Figure 2 (also shown in Figure 1), be-

ing a section on the line 33 of Figure 1, looking in the direction of the arrows; and in Figure 3 the head is shown in position wherein it engages the record supported by the stand, and prior to release of the final record to playing position,

and it shows the corresponding position of the toggle spring and other parts;

Figure 4 shows a vertical section on the line 4-4 of Figure 1, looking in the direction of the arrows; and it shows the stop lever in the position it occupies when a record is in place on the stand;

Figure 5 shows a vertical section, also on the line 4-4 of Figure 1, looking in the direction of the arrows; and it shows the stop lever in the position it occupies when the final record has been released to playing position; Figures 2, 3, 4 and 5, being on enlarged scale as compared to Figure 1;

Figure 6 shows more or less schematically the principal operating parts of the record-changer of Figure 1, including the one-cycle cam, the stoplever, the cam stopping means, the one-cycle cam driving means, and the manually operated lever (same being in its Stop position) and this figure also shows the stop means of the present invention as applied to said parts, said stop means being shown in the position which it occupies when the final record has been released to playing position, but prior to release of the trigger device by the one-cycle cam during the cyclic movement, the drive to the one-cycle cam being not yet discontinued;

Figure 7 shows a wiring diagram of the series connections of the two switch devices to the motor;

Figure 8 shows a view similar to that of Figure 6, but with the stop lever in its position occupied when a record is in place on the supporting stand, the manual control lever being shifted to its Automatic position for automatic playing of the records in succession, so that as the one-cycle cam continues its cyclic movement and releases the trigger, the switch will nevertheless not be released, but the motor operation will continue normally and progressively; and

Figure 9 shows a view similar to that of Figure 8, but with the stop lever in the position it occupies when the final record has been released, the manual control lever being still in its Automatic position, and the one-cycle cam having moved around to position where the trigger has been released, thus permitting the switch device to open the motor circuit, and discontinue current supply to said motor.

Referring now to the drawings, I have therein shown a record-changer including the turntable 10 suitably journalled for rotation on the vertical axis represented by the center pin II. This turntable is driven in suitable manner, but the scheme shown herein includes the motor shaft l2 carrying a small friction wheel l3. The friction wheel 13 engages the idler friction wheel 14 which in turn engages against the inner face of the fiange 15 extending down from the turntable I0. Normally the turntable is thus driven by a friction drive from the motor (not shown), since during normal operation it is desired that the turntable should rotate continuously. In Figure 7 the motor is shown by the armature l6 and the series field winding I! in conventional form.

The tone-arm is shown at [8 in Figure 1. It is mounted for swinging movement about the vertical axis [9, so that it can be swung outwardly far enough to clear the records on the turntable, and so that it can move inwardly towards the center pin H during the following of the record track during playing. This tone-arm is also provided with suit-able horizontal hinge means so that it can be raised to raise the stylus from the record, and so as to thereafter lower the stylus into playing engagement with the record. This is well known in this art and requires no particular description here. I will mention, however, that this raising and lowering means and also the stylus and tone-arm swinging means take the form of a one-cycle cam 20 journalled on the vertical axis 2i. This cam includes the vertically acting cam surface 22 which is engaged by the pin 23 concentric with the axis of tone-arm swinging movement, so that as the cam effects its one-cycle movement said pin is raised to raise the tone-arm, after which the tone-arm is again permitted to lower into playing engagement with the record. This cam also includes a suitable cam track (not shown) which receives and enages a cam follower pin 2 3, suitably connected to the tone-arm or to tone-arm shifting means.

51 carried by the manual control lever 3|.

The one-cycle cam normally stands in the position indicated in Figures 6 and 8. At completion of playing of a record this one-cycle cam is driven from the motor for a complete rotation, and is then disconnected from the motor drive so as to come to rest. Such drive is effected, in the scheme shown, by the idler friction wheel carried by one end of a bell-crank 26 journalled at 21, said journal being concentric with the wheel 28 which is engaged by the wheel 25. This wheel 28 is connected to a pinion (not shown) which engages av gear on the periphery of the one-cycle cam, so that when the wheel 25 engages the wheel 14 there is established a friction drive from the motor shaft to the one-cycle cam. To interrupt this driveit is only necessary to swing the bell-crank arm 26 which carries the wheel 25 clockwise a slight amount, thus carrying the wheel 25 away from the wheel Hi. When this occurs, however, the motor and the truntable may still be allowed to run, which is the usual condition during playing of a series of records.

The bell-crank includes another arm 29, and a spring 30 having one end connected to this arm, and its other end suitably anchored tends to rock the bell-crank in direction to bring and hold the wheel 25 against the wheel I4. However, by swinging the arm 29 towards the right against the force of the Spring 30, the drive to the onecycle cam is discontinued.

There is also shown the manual control lever arm 3|, journalled at the point 32. This manual control lever is movable into either of several selected positions; and in the scheme shown herein there are four such positions, including Stop, Manual, Automatic and Reject. These positions are shown in Figure 6; and a series of notches 33 is provided in the edge of this manual lever, corresponding to these several positions; and a spring actuated roller 34 is provided for successive engagement with said notches so as to retain the manual lever in any selected position under spring force. This manual control lever arrangement is shown in the aforesaid earlier application, Serial No. 607,878 and in other applications filed by me and by others; and said lever may produce various functions which it is' not necessary to discuss here, as well as the functions herein specially discussed.

There is provided a motor switch 35 carried adjacent to the notched portion of the manual lever 3|; and this switch has the contact actuating finger 35 which may be engaged by a lug The arrangement is such that as the control lever is moved clockwise from the position of Figure 6 the lug 3'! will rock the finger 36, thereby closing the motor circuit at the position of this switch; and said switch will then remain in closed position as long as the manual control lever 3| stands in any of the positions designated as Manual, "Automatic or Reject. When next this control lever is shifted back to the position shown in Figure 6, being the "Stop position, being a move- .ment of the notched portion of said lever towards the right, as the Stop position is closely approached, the finger 31 will again engage the finger 36, moving it to the circuit opening position, which is the position shownin Figure 6. Thus the circuit is then opened at the position of this switch 35, and will remain open until the control lever is again moved to any of the operating positions. This switch is shown in Figure .7 in series with the motor and another switch which. I shall presently disclose and discuss.

Mounted on the frame of the record-changer adjacent to the turntable is the stand 38 shown in Figure l and in detail in Figures 2, 3, 4 and 5. Within the stand is carried the vertical rock arm 39, j-ournalled for swinging movement on the horizontal axis 40. The edge portion of a record ll is shown as being supported by this stand or by an element carried by the stand; and in accordance with disclosures contained in my aforesaid application, Serial No. 607,878, as well as other co-pending applications, such record may be shifted slightly at the proper time to release said edge portion from the stand and thus permit said record to descend into playing position on the turntable or on records previously released onto said turntable. The upper end portion of the rock arm 39 may engage the edge portion of such record, or with an element which in turn engages the edge portion of the record; so that by rocking said arm 39 slightly at the proper time suchrecord is released. Such rocking is effected, in the scheme shown herein, in the following manner: a slide plate 32 is provided with a slot 53 which receives the lower end portion of the rock arm 39, and a, spring 44 connecting the slide plate with the rock arm tends to cause the rock arm to follow a sliding movement of the slide. Such sliding movement is effected by rocking a triangular plate 45 pivoted to the frame of the machine at the point 48 and normally retained in the position shown in Figure 6 by a spring 41. This triangular plate is pivotally connected to the slide as shown at 48, and this plate also has the downwardly extending flange 49. The onecycle cam carries a stud 56 which will engage the said flange at about the half-revolution position of the one-cycle cam, thus rocking the triangular plate, and shifting the slide 42 and rocking the rock arm to feed a record by release of same from the stand. Thus the record is released by the one-cycle cam at the proper timing of the cyclic movement.

This stand 38 carries a head element 5! which is journalled for rocking movement on the transverse axis 52. Such journalling is efiected by providing a transverse shaft which is secured to the head element 5! and rocks as said head element is raised and lowered; and said shaft is provided with a crank section 53 to which is connected the upper end of a relatively stiff spring 54, the lower .end of said spring being held by the cross pin 55 in the stand proper. The arrangement is such that when the head element is in a substantially horizontal position such as shown in Figure 4 or in Figures 2 and 3, the spring exerts a considerable force tending to lower the head element against an obstruction, but when said head element is overturned backwardly said crank will move over a dead center position so that the effect in said spring is then reversed, and the spring then tends to retain the head element in such overturned position. This head element carries the two corner pads 56 and 51, preferably of rubber or other non-abrasive material, which bear against the top face of the top record sustained by the stand, thus holding the head element in a substantially horizontal position, such as shown in Figures 3' and 4; but when no record is present on the stand this head element ma rock slightly into the position of Figure 2, such rocking being under the influence of the spring 54. This is the no-record position, and when this head element lowers to this position the stop mechanism herein disclosed becomes effective to stop the motor, as I shall now explain:

There is another rock arm 58 j ournalled in the stand 38 at the point 53 so that said rock arm may rock within a plane lying substantially at 45 degrees to the plane of rock of the rock arm 3% which releases the records. A spring 50 tends to rock this arm 58 into the position shown in Figure 4. The shaft 52 which rocks with the head element carries a crank arm (ii in position to engage a lug 62 on the rock arm 58 so that as the head element is lowered beyond the position of Figure i to that of Figure said crank 6! will rock the arm 58 against the force of the spring iii the spring 54 being capable of producing sufiiciently effective mechanical force to effect this result. On the contrary, when the head element is sustained by a record in place on the stand, or by manual raising of said head element, the rock arm 58 will be caused to follow the rocking movement of the crank B i.

There is a lever arm 63 pivoted to the frame of the machine at the point it, said lever arm being engaged by the lower end portion of the rock arm 58. A spring 64 tends to retain this lever arm 63 in engagement with the rock arm. The one-cycle cam it, or the center post thereof, carries a stop cam 65 having the shoulder 88. A slide bar 6? is provided with a slot 68 to receive the pin 69 carried by the frame of the machine, so that said slide may move back and forth but is retained against lateral movements. One end of this slide bar is connected by a link E9 to the free end or the rock lever 63 by a pin El and to the slide bar by a pin 72; and this slide bar carries a stud 13 which may be engaged by the shoulder 6B of the stop cam. Such engagement will occur if when the one-cycle cam comes around the lever arm 83 has been rocked to the position of Figure 6, due to complete lowering of the head element when no record is in place on the stand. Such engagement of the shoulder 66 with the stud 73 will shift the slide bar towards the left. There is provided another rock arm 76 pivoted on a stud 15. One end of this rock arm is in position for engagement by the end of the slide bar 68 and the other end of this rock arm M is adapted to engage the arm 22-] of the bell-crank which carries the idler wheel 25. Thus, as the shoulder 68 shifts the slide bar 88 towards the left, the head element being in fully lowered position, the wheel will be disengaged from the I wheel M, thus discontinuing drive of the onecycle cam, notwithstanding that the motor is still in operation, and the wheel :4 is still being driven thereby.

All the foregoing features and elements are disclosed in my aforesaid application, Serial No. 607,878, and other applications herein referred to, and these features do not of themselves constitute the subject-matter of claims of the present application, but are disclosed herein since they are related to the stop device elements which I shall no disclose in particularity.

A bell-crank i6 is pivoted to the frame of the machine at the point H. To the lower end portion of the rock arm 53 there is connected the link '28; and companion link 19 has one end connected to the belhcrank 76. These links 18 and i9 have the loops 8i] and 3! which receive the companion link portions, so that the two links may shift with respect to each other. A compression spring 82 is placed between these loops, tending to shorten or telescope the two links together, and thus to reduce the distance between the rock arms 53 and it. A stop 85 is securedto the link 79 in position to limit the shift of the links rela- 8 tive to each other under influence of the spring 82. Such condition is shown in Figures 8 and 9 wherein it will be seen that the loop 80 is in engagement with the stop 83.

There is a lever arm 84 pivoted to the frame at the point 85. This lever arm has the lug 88 in position to engage the finger 8'! formed down from the bell crank "16; and as long as this lever arm stands in the position shown in Figures 6 and 8 this acts as a hook to prevent the bellcrank 16 from rocking to the position of Figure 9; but as soon as this lever arm or hook arm is rocked to the position of Figure 9 the bell-crank is disengaged and permitted to rock if other factors permit such movement to occur. A spring 96 tends to retain this hook in its lowered position of Figures 6 and 8 to retain the bell-crank in locked position.

There is a stop switch 81 carried by the frame of the machine, said switch including the contacts 88 and 89 which normally tend to engage each other; but the contact 89 may be engaged by an adjustable pin so on the bell-crank. These parts are so adjusted that when the bell-crank is locked in position of Figures 6 and 8 the contacts will engage each other, closing the circuit at th1s point; but when the bell-crank is released and permitted to rise the pin 9-9 will raise the contact 89 from the contact 83, thus opening the circuit at this point.

The one-cycle cam carries a stud 91 which, when the said cam comes around to the proper position, will engage the end of the lever arm 8-3, rocking the same clockwise and thus releasing the hook from. its locking engagement with the bell-crank. The parts are so proportioned that such engagement of this stud 9| with the lever arm will occur just prior to disengagement of the wheel 25 from the wheel l4, when use is made of the stop-cam 85, so that opening of the motor circuit will occur at substantially the same time as disengagement of the drive to the one-cycle cam, when the stop device including the stopcam is embodied in the combination. In any case it is desired that tripping of the hook should occur prior to engagement of the stud 50 with the flange 49 for record release, and also prior to re-setting of the tone-arm on the record, stopping occurring preferably while the tone-arm is in its extreme outwardly moved position.

The switch 8'1 is placed in series with the switch 35, as shown in Figure '7, so that even when the switch 35 remains in closed position, the opening of the switch 81 by disengagement of the contacts 88 and 89 from each other will bring the machine to a stop.

It will be seen that under proper conditions the movement of the one-cycle cam will thus ensure opening of the motor circuit at a specified position of the one-cycle cam; whereas, under other conditions the tripping of the hook by the movement of the one-cycle cam will not serve to open the switch 87*. I shall presently analyze these conditions further; but at this point I disclose the means whereby the bell-crank 16 may be re-set intentionally to thereby re-close the switch and permit further motor operation to occur. For this purpose I have provided a link 92 having one end connected to the manual con trol lever 3| by a pin 93; and the other end portion of this link is provided wtih a slot M which receives a pin 95 on the bell-crank lever with a lost motion. These parts are so proportioned that when the manual control lever is rocked to its Reject" position momentarily, the lost motion of this pin and slot connection will be taken up and the bell-crank l6 restored to its position of Figures 6 and 8 for closing of the circuit at the position of the switch 81 Then, when the manual control lever is moved back to its Automatic or to its Manual position, the bell-crank 16 will be retained in the closed circuit position due to locking of the hook arm element 84 in manner previously described. However it is to be noted that such back movement of the manual control lever will not bring the other or right hand end of the slot as into engagement with the pin 95 until the Stop position of the manual control lever is finally reached as shown in Figure 6.

The following analysis of operations is new in order:

Assuming the motor switch 35 to be closed and the parts to be in the position shown in Figure 8, the manual control lever being in the Automatic position, the switch 81 being closed by a previous operation, and a record being in place on the stand 38, normal operation of the onecycle cam will occur, said cam being brought into one-cycle operation in normal manner and proceeding through its complete cyclic movement. If this movement serves to release the last record which is in place on the stand, then the head element 5i will fall to the position of Figures 2 and 5, causing the rock arm 58 to move from the position of Figure 4 to that of Figure 5. Correspondingly, the link 18 will be moved from the position of Figure 8 to that of Figures 6 and 9, This will serve, assuming the bell-crank it to be still locked by the hook lever 84, to compress the spring 82, since the link element F9 is so far unable to follow the movement of the link element 18. However by this very operation the loop 80 is carried away from the stop collar 33 as shown in Figure 6. Thereafter, when the onecycle cam is rotated after completion of the record then in place (being the last record), when the stud 9| comes into engagement with the lever arm 84 the hook will be released, and the link 79 will be permitted to rock the bell-crank it, under influence of the spring 82. This will bring the adjustable pin 9!! into engagement with the switch leaf 89 and open the circuit into the position of Figure 9. As this has occurred the collar 83 will finally come into engagement with the loop 80, as also shown in Figure 9. The circuit is thus opened at the switch 81* automatically, and irrespective of the fact that the switch 35 remains closed.

Now it is noted that as soon as the stud 55 has tripped the hook in the foregoing manner, the switch will open, thus cutting off current from the motor; but there will still be a short interval of rotation of the one-cycle cam, due to inertia of the various parts. It is noted that this fact will ensure that the stud ill will move far enough over after actual cut-off of current to release the hook arm so that when the parts are again to be set to closed circuit position proper functioning will occur. In connection with this operation it is also noted that when the bell-crank it is re a leased to open the circuit the full movement of After the parts have been actuated to the position shown in Figure 9 the circuit may be again closed at the switch 87* in either of two manners. If the head element 5! should be raised by a manual operation to its normal position or higher, as for insertion of additional records onto the stand 38, the link '18 will be moved to the position of Figure 8, thus pressing the link 19 with it to the position of Figures :8 and 6, and moving the bell-crank 15 into the closed circuit position, releasing the hook into its locking position, and then looking the bell-crank in the closed circuit position; or, if the manual control lever 3! should be intentionally moved over to the Reject position, not illustrated in such position, the link 92 will be drawn over far enough to take up the lost motion of the pin and slot connection, and to also draw the bell-crank down with it far enough to permit the hook to engage with and lock the bell-crank in the closed circuit position. Thereafter said manual control lever maybe again permitted to move to any less moved position, such as the Automatic position, which is the one shown in Figures 8 and 9. Thereafter functioning may proceed as in the normal manner.

It is noted that the spring 82 need be light only, since the function of this spring is to draw the bell-crank 56 up to disengage the switch contacts when such operation is permitted; that the spring 54 acts in the same efiective direction as the spring 54, and that the spring '64 merely serves to cause the lever 53 to follow the rock arm 53 in its returning movement when the head element 5| is raised; and that the spring 9'6 may be light, since its function is to ensure setting of the hook lever when the proper time arrives for that function.

It is noted that in order to avoid interference between the lever arm or trigger 84 and the stud 24 of the one-cycle cam which stud rocks the triangular plate 45, I have placed the lever arm or trigger 84 at a lower elevation than the onecycle cam, so that the end portion of this lever arm may reach beneath said cam, and correspondingly the stud M which trips this lever arm projects downwardly to proper position for ensuring correct functioning of the lever arm or trig er.

I claim:

1. In a record-changing phonograph having a turntable, a motor, a tone arm, a one-cycle cam, connections between said cam and said tone arm to control tone-arm movements when said cam is moved through one cycle of its movements, means to support a record above the turntable in nonplaying position, a pivoted member rested on said record and adapted to fall about its pivot in the absence of said record, link means positioned to be displaced from a rest position by said member in the fallen position, a bell crank connected at one end to said link to be rotated by said link when displaced, a lock positioned normally to prevent rotation of said bell crank, a pin on said one-cycle cam positioned to engage said lock and unlock said bell crank once during each rotation, and a switch in the motor circuit positioned to be opened by said bell crank when rotated.

2. Apparatus in accordance with claim 1 wherein said pin is so located on said one-cycle cam that said lock is unlocked at the time when the tone arm is clear of the turntable,

3. Apparatus in accordance with claim 1 iii wherein said link means is in two parts which are resiliently connected together to prevent straining said bell crank.

4. Apparatus in accordance with claim 1 including means connected to said bell crank to reset said switch to locked position and a spring connected to said lock to restore the same to locked position.

SVEN A. STOLBERG.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number 12 UNITED STATES PATENTS Name Date Allen July 17, 1934 Ofien Sept. 8, 1942 FOREIGN PATENTS Country Date Great Britain June 14, 1933 Great Britain Jan. 4, 1937 

